Pressure sensors can be utilized to measure the spatial distribution of pressure across a surface due to an environment of fluid or due to contact with the surface of an object. While contact pressure sensors target pressures of approximately 10.sup.4 Pascals (Pa), many fluid pressure sensing applications target pressures from 1 to 1000 Pa but also require sensitivities of approximately 1 Pa or less. Uses for such fluid pressure profiles include determining fluid dynamic pressure distribution on surfaces to optimize vehicle design, measuring the viscoelastic properties of a fluid in a rotating cone rheometer, and detecting turbulent flow in an enclosed conduit to optimize flow rate. In these high resolution applications, fluid pressure sensors must be sensitive to small differences in pressure over an area, reliable while withstanding high pressure contact during installation and cleaning, and inexpensive to fabricate.
Sensors for pressure profiles can be constructed by placing multiple individual sensors adjacent to each other, where each has a separate membrane. U.S. Pat. No. 5,225,959 issued Jul. 6, 1993, provides an example of a multiple diaphragm contact sensor array. Besides using contact transducers, sensor arrays of this type also have certain disadvantages including (a) spacing is increased between transducers and resolution and sensitivity is decreased since each diaphragm has only one transducer and (b) installation of numerous individual sensors can be difficult to align and to clean. An example of a multiple element, contact sensor with a single diaphragm is shown in U.S. Pat. No. 5,184,515 issued Feb. 9, 1993. However, the sensing elements are piezoresistors disposed within the diaphragm itself. This type of sensor is more susceptible to damage due to contact during installation and cleaning, more susceptible to thermal variations, and more complex and expensive to fabricate than non-contact sensing methods since the piezoresistors are embedded in the membrane.
A need therefore exists for an improved fluid pressure sensor/sensor array which provides high resolution, sensitivity which can be easily controlled based on anticipated or detected pressure range, and reliable pressure measurements with easy installation and low fabrication cost.